Field of the Invention
The present invention relates to an image processing technique for raising print speed.
Description of the Related Art
An image processing apparatus which includes a print function for printing an image on paper media using toner, stores the toner in a container in a printing unit. The toner container in the printing unit is divided into two layers, i.e., a first layer storing original toner and a second layer storing toner to be used for immediate printing. The image forming apparatus performs control for replenishing the second layer with the toner from the first layer by an amount used in the second layer each time printing is performed. The image processing apparatus determines the amount of toner to replenish the second layer by calculating a video count value when generating image data to be printed. The video count value is a value indicating a toner amount to be used in printing and is defined by each pixel of the image data integrated with a density value thereof.
More specifically, the image processing apparatus performs halftone processing, i.e., converts a multi-valued image in a red, green, and blue (RGB) format input from an external device or a reading unit to a binary image for each color toner (e.g., cyan (C), magenta (M), yellow (Y), and black (K)), to generate print image data. The image processing apparatus measures the video count in halftone processing using hardware, notifies the printing unit of the video count value, and performs toner replenishment.
If the toner amount actually used is different from the toner amount replenished after printing, there is excess or deficiency in the toner amount stored in the second layer and to be used for immediate printing. In such a case, normal printing density cannot be maintained, and thus printing may result in light or excessively deep color print. In particular, an image processing apparatus in which a capacity of the second layer is small is greatly affected by such a difference. It is thus necessary for the image processing apparatus to accurately measure the video count value.
As described above, the image processing apparatus prints the print image data obtained by performing halftone processing on the data input from the external device or the reading unit. Further, the image processing apparatus includes an image combining function for combining the halftone-processed print image data with the binary image generated within the apparatus and printing the combined image.
In such a case, it is necessary to add the toner amount used for printing a composite image portion generated in the image processing apparatus, in addition to the toner amount used for printing the input image portion which has been halftone-processed, to determine the toner amount to be used. It is thus necessary to separately calculate the video count value of the composite image portion.
According to a conventional technique, chromatic color pixels and the density values thereof are analyzed using software with respect to the generated composite image and the video count value is then calculated. Further, Japanese Patent Application Laid-Open No. 2012-141497 discusses a method for calculating the video count value of an output image after performing image combination by subtracting the video count value of the composited image from the video count value of a document image.
However, according to the conventional technique, it takes time to calculate a video account value of a composite image since it is necessary to perform image analysis using software to calculate the video count value. As a result, printing time becomes longer taking time required for calculating the video count value, and performance is thus deteriorated.